foo.cc:30:8: error: stray '\357' in program
   int x； 
        ^
foo.cc:30:9: error: stray '\274' in program
   int x； 
         ^
foo.cc:30:10: error: stray '\233' in program
   int x； 
          ^
foo.cc: In function 'int main()':
foo.cc:31:3: error: expected initializer before 'add'
   add(x,i);
   ^~~
foo.cc:27:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=n;i++) scanf("%d",&f[i][1]);
                        ~~~~~^~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。